diff options
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 52b861da15..e2607c0c1a 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -849,11 +849,15 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { } Instruction *InstCombiner::visitDiv(BinaryOperator &I) { - // div X, 1 == X if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) { + // div X, 1 == X if (RHS->equalsInt(1)) return ReplaceInstUsesWith(I, I.getOperand(0)); + // div X, -1 == -X + if (RHS->isAllOnesValue()) + return BinaryOperator::createNeg(I.getOperand(0)); + // Check to see if this is an unsigned division with an exact power of 2, // if so, convert to a right shift. if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS)) |